Category Distinguishability and Observer Agreement

It is common in the medical, biological, and social sciences for the categories into which an object is classified not to have a fully objective definition. Theoretically speaking the categories are therefore not completely distinguishable. The practical extent of their distinguishability can be measured when two expert observers classify the same sample of objects. It is shown, under reasonable assumptions, that the matrix of joint classification probabilities is quasi-symmetric, and that the symmetric matrix component is non-negative definite. The degree of distinguishability between two categories is defined and is used to give a measure of overall category distinguishability. It is argued that the kappa measure of observer agreement is unsatisfactory as a measure of overall category distinguishability.     

Modeling for insights,not numbers: the experiences of the energy modeling forum

It has often been contended that the primary goal of policy modeling should be the insights quantitative models can provide, not the precise-looking projections—i.e. numbers—they can produce for any given scenario. Students of the energy policy process, in particular, have noted that preoccupation with the plethora of detailed quantitative results produced by large-scale computer models has substantially impeded their influence on key policy decisions. The creation of the Energy Modeling Forum (EMF) at Stanford University in 1976 represents one potential remedy for that situation. The EMF was formed to foster better communication between the builders and users of energy models in energy planning and policy analysis. The EMF operates through ad hoc working groups, composed of national and, more recently, international energy modeling and policy experts. These working groups conduct studies concentrating on a single energy topic. The diversity of backgrounds of the working group members ensures that the language of the EMF studies is English, not computer. Each working group identifies existing models relevant to the study's focus. A series of tests is then designed by the group to illuminate the models' basic structure and behavior. A comparison of results is published in a widely distributed report that identifies the models' strengths and weaknesses in the context of the study's topic. Seven EMF studies have been initiated to date: (1) Energy and the economy, (2) Coal in transition, (3) Electric load forecasting, (4) Aggregate elasticity of energy demand, (5) US oil and gas supply, (6) World oil and (7) Macroeconomic impacts of energy shocks. Each EMF study has broadened the understanding of the nature of the relevant policy issues and the models that have been, are, or could be used to address them. The present paper describes how each study's key insights were developed in the context of a simplified analytical framework that provided the proper perspective for understanding the model results.     

A REGRESSION- TYPE ESTIMATOR IN SAMPLING WITH PPS AND WITH REPLACEMENT

A regression-type estimator is proposed for the population total of a character y , when sample-units are selected with probability proportional to some measure of size z (pps) and with replacement; and the information on yet another variate x is used. The proposed estimator is shown to be superior to the well-known estimator (pps with replacement), and the ratio estimator (pps with replacement). It is also shown to be superior to the simple random estimator under some general conditions.     

A general guideline for management of risk from carcinogens

A simple relationship is formulated that helps to discriminate between acceptable and unacceptable individual lifetime risks (RL) to populations that are exposed to chemical carcinogens. The relationship is an empirical one and is developed using objective risk data as well as subjective risk levels that have found substantial acceptance among those concerned with carcinogenic risk assessment issues. The expression sets acceptable levels of lifetime carcinogenic risk and is a function of the total population exposed to the carcinogen. Its use in risk assessment and risk management provides guidance in distinguishing those carcinogens that should be regulated because of the health hazard they pose from those whose regulation may not be needed.     

How strategic decisions are made

The aim of this article is to shed some light on how strategic decisions and actions occur in organizations. The fundamental argument is that the traditional literature fails to provide an adequate understanding of how such decisions are made and that a new focus is needed. Drawing on organizational theory, the author approaches a new focus on decision-making, having the first described the traditional approaches.     

Automatic selection of the proper family for simultaneous confidence intervals

Statisticians often employ simultaneous confidence intervals to reduce the likelihood of their drawing false conclusions when they must make a number of comparisons. To do this properly, it is necessary to consider the family of comparisons over which simultaneous confidence must be assured. Sometimes it is not clear what family of comparisons is appropriate. We describe how computer software can monitor the types of contrasts a user examines, and select the smallest family of contrasts that is likely to be of interest. We also describe how to calculate simultaneous confidence intervals for these families using a hybrid of the Bonferroni and Scheffé methods. Our method is especially suitable for problems with discrete and continuous predictors.